片段未使用Android 5.0工具栏小部件显示在ActionBarActivity中

Question

当我运行我的应用程序时,MainFragment根本没有显示在扩展ActionBarActivity的活动中.我确实查过这篇文章,但它没有帮我解决我的问题.这是我的活动和片段:

activity_main.xml中:

public class MainActivity extends ActionBarActivity {

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    if (savedInstanceState == null) {
        getFragmentManager().beginTransaction()
                .add(R.id.container, new MainFragment())
                .commit();
    }

    Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
    setSupportActionBar(toolbar);
}

@Override
public boolean onCreateOptionsMenu(Menu menu) {
    // Inflate the menu; this adds items to the action bar if it is present.
    getMenuInflater().inflate(R.menu.main, menu);
    return true;
}

@Override
public boolean onOptionsItemSelected(MenuItem item) {
    // Handle action bar item clicks here. The action bar will
    // automatically handle clicks on the Home/Up button, so long
    // as you specify a parent activity in AndroidManifest.xml.
    int id = item.getItemId();
    if (id == R.id.action_settings) {
        return true;
    }
    return super.onOptionsItemSelected(item);
  }
}

fragment_main.xml:

public class MainFragment extends Fragment {

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
                         Bundle savedInstanceState) {
    View rootView = inflater.inflate(R.layout.fragment_main, container, false);
    return rootView;
    }
}

我不认为我需要在这里引用任何xml ...一切正常,直到我在activity_main.xml中扩展ActionBarActivity而不是Activity.

编辑:添加xml以防万一:

activity_main.xml中:

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:id="@+id/container"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".MainActivity"
tools:ignore="MergeRootFrame" >

<include layout="@layout/toolbar" />

</LinearLayout>

fragment_main.xml:

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
android:paddingBottom="@dimen/activity_vertical_margin"
tools:context=".MainActivity$PlaceholderFragment">

// There are several text views and buttons I will not add to this code, 
// but just know that this fragment isn't blank.

</RelativeLayout>

编辑2:我已经完成了一些测试,每当我从activity_main.xml中删除工具栏时,片段都会显示,并且没有操作栏(因为这是我为了使用工具栏而设置到我的应用程序的主题) .所以这里是我的toolbar.xml的xml,我在activity_main.xml中使用它.也许我做错了它隐藏我的整个片段？

tl; dr:fragment显示从activity_main.xml中删除此行代码时:

<include layout="@layout/toolbar" />

这个在activity_main.xml中:

Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
    setSupportActionBar(toolbar);

Answer 1

刚刚在AOSP上打开了一个错误报告.我现在发现并使用的解决方案是在add()内部调用post().

new Handler().post(new Runnable() {
    @Override
    public void run() {
        getFragmentManager().beginTransaction()
            .add(R.id.container, new MainFragment())
            .commit();
    }
});